The aquifer storage system in Bonn supplies up to 80% of the heat and cold in three buildings covering a total area of 60,000 m². Credit: Paul Fleuchaus, KIT
Conventional geothermal heat pumps are becoming increasingly popular in Germany. About 350,000 systems are installed in new buildings in particular. "These geothermal heat pumps are mainly used for heating in winter," says Philipp Blum. "Aquifer storage systems, by contrast, can do both: cooling in summer and heating in winter," he says.
Paul Fleuchaus, doctoral researcher of AGW, adds: "When constructing new buildings in Germany, hardly anybody considers energy supply by aquifer storage systems. This is different in the Netherlands," he says. "There, more than 2800 systems are operated successfully." Due to their large capacity, aquifer storage systems are suited in particular for large buildings, such as museums, hospitals, office buildings, or hotels. Also in residential areas, aquifer storage systems combined with local heat networks can be used. In the Netherlands, the technology is also applied for industrial complexes, such as greenhouses or computing centers. According to calculations of the scientists, a return on investment is often reached after two to ten years already.
The scientists of the project GeoSpeicher.bw say that thanks to the geological conditions, a number of regions in Germany and Europe, but also worldwide are suited for aquifer-based geothermal energy supply. The experts of Karlsruhe Institute of Technology, the universities of Heidelberg and Stuttgart, and the universities of applied sciences in Biberach and Offenburg also study heat and cold storage with the help of tunnel systems, such as the Rosensteintunnel in Stuttgart.
"We expect energy consumption for air conditioning systems to increase by a factor of 33 by 2100," says Paul Fleuchaus. "The recent collapse of the power grid in parts of California shows that this can be managed with neither the existing grid nor conventional energy carriers," he says. To identify alternatives, technical analyses are accompanied in the project GeoSpeicher.bw by studies relating to public acceptance and current legislation. "In the Netherlands, we found that close cooperation of authorities, scientists, the public, and utility companies is very effective," Fleuchaus says.